The application of separating methods in CTL is very extensive. Techniques such as gas chromatography (GC and GC/MS), liquid chromatography (HPLC), thin-layer chromatography (TLC) are used. In the year 2000 the planar gel electroforesis was installed in CTL, as well. This method is used especially in the protein analysis. Additionally, some laboratories were equipped with the system of capillary isotachophoresis.
CTL is equipped with the high resolution GC chromatographs with autosampler, liquid chromatographs with autosampler and the TLC set including developing chambers, plates, spray bottles, UV-lamp and box. In addition, the wide range of accessories consisting of e.g. MS, FID, DAD and RI detectors, post-column reactor, column filling pump, UV-VIS and conductivity detectors are used.
The above-described equipment enables the analysis of mixtures of organic compounds in general. The organic mixtures in general depending on their physical properties are analysed by GC and/or HPLC methods. Ionised compounds (both organic and inorganic) especially in water matrices are analysed by the methods of capillary isotachoforesis. Methods of TLC are used mainly for screening of some groups of materials (drugs, pesticides, dyes and spices) or for fast, qualitative and preliminary tests.
The most important commodities analysed by the methods of gas chromatography involve spirit and alcoholic beverages including denaturants, hydrocarbon fuels and their mixtures with fatty acids methylesters (so called „biodiesel“), natural fats, oils and waxes and products obtained by their chemical treatment, petroleum spirits and solvent mixtures. The GC/MS technique, which combines the ability to separate multicomponent mixtures with the possibility of identification of each separated component, is used either for the general identification of unknown materials or for characterisation of common products, e.g. essential oil mixtures, pesticides, disinfectants, drugs, denaturants and other organic products of chapters 29, 30, 33 of the Harmonised System.
Liquid chromatography (HPLC) is the principal technique for analysis of food, food preparations and supplements and several other chemical compounds including mono- and disaccharides, starch, conservants, vitamins, organic acids, alcohols and glycols, alkaloids, artificial sweeteners and other components of foodstuffs and denaturizing agents.
The methods of principal importance are those, which give information about products with excise duty namely spirits, denaturants, fuels and “biodiesel”. Some other methods are applied for distinguishing between the products with double rate of VAT, namely the products of chapters 13, 15, 17, 18, 19, 20, 21, 29, 30, 33 and 36 of Harmonised System.